1. Field of the Invention
The invention is generally related to preventing the spread of the common cold and protecting individuals from becoming infected with viruses which cause the common cold. More particularly, the invention is related to the use of a composition which effectively kills rhinoviruses present on a person's hands and continues to kill rhinoviruses for a period of hours after application of the composition.
2. Description of the Prior Art
Rhinoviruses are the most significant microorganisms in causing the acute respiratory illness referred to both physicians and lay persons as the "common cold". Other viruses, such as parainfluenza viruses, respiratory syncytial viruses, enteroviruses, and coronaviruses, are known to cause symptoms of the "common cold"; however, rhinoviruses are now thought to cause the greatest amount of cases of the common cold. Rhinoviruses have also been found to be among the most difficult to kill of the cold causing viruses. While the molecular biology of rhinoviruses is now understood in great detail, the progress in determining effective methods for preventing colds caused by rhinoviruses and for preventing the spread of the virus to non-infected subjects has been slow.
Gwaltney et al., Annals of Internal Medicine, 88:463-467 (1978) reports that rhinovirus colds are commonly spread amongst a human population by hand-to-hand transmission. That is, one subject with a rhinovirus cold will have a brief physical contact with another subject. By virtue of the physical contact, rhinovirus particles will be present on the hands of the contacted person. The contacted person will then become infected with the rhinovirus by placing contaminated fingers on their nasal and conjunctival mucosa. This hand contact/self inoculation concept for rhinovirus transmission is supported by other research groups that have demonstrated that rhinovirus is recoverable from the hands of a large number of patients infected with rhinovirus.
Hendley et al., Antimicrobial Agents and Chemotherapy, 14:690-694 (1978) explored the idea of interrupting the spread of rhinoviruses through the use of antimicrobial liquids and foams applied to the hands. While it is acknowledged that frequent hand washing with ordinary soap and water will mechanically remove viruses from the hands and, thus, reduce the spread of rhinovirus colds, washing one's hands multiple times is irritating to the skin. Therefore, an objective of Hendley et al. was to evaluate the virucidal activity of certain agents that were believed to be non-irritating to the skin after multiple applications so that the need for mechanical removal of the virus by frequent washing was avoided. In Hendley et al., liquids containing dilute iodine in ethyl alcohol or water, and foams containing ethyl alcohol, benzalkonium chloride (BAK), and hexachlorophene were evaluated. The most effective treatment antiviral compositions contained iodine. In addition to immediately killing rhinoviruses on contact, iodine solutions were found to have a residual killing capacity that would inactivate rhinoviruses introduced on a subject's fingers for up to one hour after iodine application. By contrast, ethyl alcohol alone was not effective, and the combination of ethyl alcohol with BAK was fairly ineffective in killing rhinoviruses.
Despite the teachings in Hendley et al., iodine based washes are unsuitable for wide spread use in preventing the spread of rhinovirus induced colds. This is because iodine will cause some brown staining of a patient's hands and is somewhat irritating to the skin.
Hayden et al., Antimicrobial Agents and Chemotherapy, 26:928-929 (1984) also discussed the concept of interrupting the hand-to-hand transmission of rhinovirus colds through the use of a safe, cosmetically acceptable hand lotion which has lasting virucidal activity. In Hayden et al., it was discovered that hand lotions containing 2% glutaric acid were more effective than placebo in inactivating certain types of rhinovirus. However, Hayden et al. reports that the glutaric acid containing lotions were not effective against a full spectrum of rhinovirus serotypes.
The Kimberly-Clark Co. has produced a "virucidal tissue" designed for use by persons infected with the common cold. The virucidal tissue includes citric acid, malic acid and sodium lauryl sulfate. Hayden et al., Journal of Infectious Diseases 152:493-407 (1985) reported that use of paper tissues, whether treated with virus-killing substances (Kimberly Clark) or untreated, can interrupt the hand-to-hand transmission of viruses. Hence, no distinct advantage in preventing the spread of rhinovirus colds can be attributed to the use of virucidal tissues.
Furthermore, virucidal tissues would have to be used appropriately by infected individuals in order to be effective, not "well" individuals who are not currently suffering from the common cold. In many settings, e.g., the family home, elementary school, in college dormitories, etc., people are in close contact for extended periods of time. As discussed above, this close contact is liable to result in an infected individual transmitting the virus to an unprotected individual. It would be advantageous to have a treatment regime which can be used by both infected and non-infected individuals to halt the spread of the rhinovirus induced colds.